Method for lowering contents of oxygen and nitrogen in molten steel at smelting end in semisteel smelting converter

Abstract

The invention provides a method for lowering the contents of oxygen and nitrogen in molten steel at the smelting end in a semisteel smelting converter. The method comprises the following steps: before the blowing and smelting process, adding waste steel into semisteel in the converter, thereby controlling the content of carbon in the molten steel to be between 3.0% and 3.5% by weight and the temperature to be between 1250 DEG C and 1274 DEG C; and adopting different bottom-blowing modes during the oxygen top-blowing process in the converter, wherein carrying out the bottom-blowing on carbon dioxide before the oxygen blowing quantity during the semisteel smelting reaches 75% of the total oxygen blowing quantity during the whole semisteel smelting process; carrying out the bottom-blowing on argon before the oxygen blowing quantity during the semisteel smelting reaches 75% to 90% of the total oxygen blowing quantity during the whole semisteel smelting process; stopping the oxygen top-blowing when the oxygen blowing quantity during the semisteel smelting reaches 90% of the total oxygen blowing quantity during the whole semisteel smelting process; and carrying out the bottom-blowing on the carbon dioxide until the steel tapping. When the method provided by the invention is used for smelting the semisteel, the problem that molten steel and steel slags at the smelting end are high in oxidability due to the semisteel steel-smelting reblowing is solved. In addition, the oxygen content and the nitrogen content in the molten steel at the smelting end in the converter are lowered; and the total iron content in converter slags at the end is low.

Description

technical field

[0001] The invention relates to the technical field of converter steelmaking, and more specifically relates to a method for controlling the oxygen and nitrogen content of molten steel at the end point of semi-steelmaking converter smelting. Background technique

[0002] Because the carbon mass percentage of semi-steel steelmaking is lower than that of ordinary molten iron (3.4% to 4.0%), the content of silicon and manganese heating slagging elements in semi-steel is traces, so semi-steel smelting has the advantages of less acidic slag-forming substances in the blowing process, The slag system has a single component and insufficient heat, which makes semi-steel steelmaking more difficult than molten iron steelmaking, and the number of deep blowing furnaces is higher. Supplementary blowing in the later stage of converter smelting will lead to higher oxygen activity of molten steel at the end point and higher total iron content of slag at the end point. At the s...